DE2057363A1 - Pressure reducing valve - Google Patents

Description

Walter Langhoff Munich, November 20th. 1970

^Pa * enf _anvvaIt My reference: SH - 772

⁸ Munich 81
Wfssmannitrasse 14

description
to the company's patent application

The Cessna Aircraft Company, 5800 East Pawnee Road, Wichita,

Kansas 67200, U ₀ S. A ₀

concerning

Pressure reducing valve

The invention relates to pressure actuated flow control valves and more particularly relates to a pressure reducing valve.

Pressure reducing valves respond to pressure increases in the inflow line and regulate the pressure in the discharge line to a desired one As is known, Niveauc pressure reducing valves comprise a valve member which is actuated by hydraulic pressure and which supplies fluid " controls flow to the valve outlet. The valve member is pretensioned by a spring which counteracts the pressure is, so that the valve member plays into a position of equilibrium between the fluid pressure force and the spring force.

With the known pressure reducing valves there is generally the problem to achieve a correct response to the inlet pressure, in particular undesired movement of the valve member so that this is neither too slow nor too fast

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responds to the inlet pressure and thereby becomes uncontrolled Vibrations, valve flutter or excessive flow and pressure fluctuations result in ο

The invention is based on the object of creating a pressure reducing valve which works stably, responds quickly and is low Causes operating noises and thus leads to better machine behavior »

The invention is based on a pressure reducing valve with a valve housing having an inlet and an outlet, which has a valve seat on the inlet side, against which an axially movable valve member is biased by means of a spring device, the valve member in the raised position providing a flow connection between the inlet and the Outlet produces "and solves the problem posed by the fact that the spring device comprises an undamped spring member and a damped spring member, the arrangement being such that when a certain pressure is exceeded, the undamped spring member is predominantly actuated first" The spring device thus comprises at least two spring members that act on the valve closing member (valve member). The reaction of the attenuated valve member become longer than that of the undamped valve member so that the latter ansprucht rapidly to pressure changes while the damped spring element is additionally operated during long press ₀

In a preferred embodiment, two spring elements are provided, which are arranged tightly next to one another, the damped spring element over the undamped spring element acts and the latter acts on the valve member = A movement of the valve member caused by the prevailing pressure after a ~ other the compression of the undamped spring element and then of the damped spring element α This acts as a counter seat for the undamped spring element during compression

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· »3 -

the same ο The damping of one spring element is provided by a hydraulic damping chamber reached »

The main advantage of the pressure reducing valve according to the invention is in that the reaction rate is as fast as with undamped valves, but that normally with these encountered instabilities are avoided. The pressure reducing valve according to the invention can be used in particular in systems where there is a certain superatmospheric back pressure on the outlet side of the valve. Another advantage lies in the fact that the relationship between pressure and flow strength runs relatively flat, as is desirable in such valves =

The invention is described below with reference to a schematic drawing additionally described using an exemplary embodiment.

The only figure shows a longitudinal section through a Pressure reducing valve according to the invention.

The pressure reducing valve 13 shown in the drawing comprises a housing 10 with a high pressure chamber 11 and a low pressure chamber 12, which is in communication with a low pressure fluid reservoir is ο The actual pressure reducing valve is screwed into the housing 10 and extends through the hole H »in the sameο There can be a hydraulic connection between the chambers 11 and 12 establish and effect a drainage of fluid from the chamber 11 into the chamber 12 and prevent that in the chamber 11 the pressure is too high »

The pressure reducing valve 13 comprises a valve housing 15 into which • a valve seat part 16 is inserted an inner bore 18, and the valve seat part 16 is provided with an inner bore 17. There are also transverse bores in both parts 20 or »19 are provided, which connect the holes

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to the Niederdruckkainmer 12 or _o the high pressure chamber to produce 11 and serve as inlet and outlet ports "within the valve seat member 16, a valve seat 22 is held by a snap ring 21 =, the valve seat is provided with a drilling which the frusto-conical outer surface 27 of a valve member 23 snugly in the valve closed position receives _o the valve member 23 is dee in the inner bore 17 valve seat member arranged to be movable 16 and has a centrally "bore 24 which extends through the valve member 23" the left end of the valve member is provided with outlet openings 25, which the Bring bores 24 and 18 in connection with one another and allow an optional connection to be established between the chambers 11 and 12 via the bore 24 and the opening 25. A seal 26 inserted into the housing prevents a leakage flow from the chamber 11.

The outer portion of the conical surface 27 of the valve member 23 is exposed to the pressure in the chamber 11 via the transverse bore 19 A sufficiently high pressure would lift the valve member to the left from the valve seat 22 and open the valve "" so that Fluid through the transverse bore 19 and the inner bore 24 into the Low pressure chamber 12 reaches »This hydraulic opening force counteracts a biasing force which is generated by a spring device 28 which engages the valve member and this biased against the valve seat

The spring device 28 comprises two helical compression springs 29 and 30, which are housed in the bore 18 and arranged one behind the other between the closed end of the valve housing 15 and the valve member 23 _o Between the two springs there is a pin 31 with an outwardly protruding flange 32 »The pin has a conical end pointing towards the valve member 23, which serves as a flow deflection device and the flow flowing out of the chamber 11 through the bore 24 to the outside

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deflected by the spring 29, which together ™ is pressed and thereby reduces the flow cross-section ο The deflected flow flows through the recesses 25 and the transverse bores 20 into the chamber 12 »

The flange 32 has a circular edge which is adapted to the bore 18 so that the edge with this bore a annular throttle point 35 formed This throttle point separates two fluid spaces 33 and 34 from each other, which through the two Sides of the flange 32 and the walls of the bore 18 are formed, The valve housing 15 has a larger number of transverse bores 20, so that the fluid space 33 with the low-pressure chamber 12 in terms of flow is in connectionο On the other hand, fluid from the Space 34 only exit via the annular throttle point 35, so that thereby a hydraulic damping chamber 34 is formed, which the speed of movement of the compression spring 30 and thus also of the valve member 23 is limited «The throttle point 35 is dimensioned so that that the desired damping properties and a desired movement behavior of the valve member 23 are achieved Throttle point between the fluid spaces 33 and 34 can also through other structural devices may be formed, for example by one or more precisely dimensioned openings in the pin 31 or by Openings which connect the fluid space 34 directly to the low pressure chamber 12 connect »

In the closed position, the springs 20 and 30 are subjected to a certain compressive force by one or more washers 36 adjusted to the correct preload on the valve member 23 when the pressure in the chamber 11 is a predetermined Exceeds the value, the hydraulic force exerted on the valve member 23 is greater than the biasing force of the springs 29 and 30, so that the valve member is moved to the left into the open position * Initially the spring 29

BATH ORIGINAL 109824/1136

Gegan the flange 32 is pressed, since the fluid chamber 3k , which acts as a damping device, prevents sudden compression of the spring 30. The spring 29 alone has a relatively high spring constant due to its relatively small length, so that the counterforce exerted by the spring increases very quickly when the spring is compressed, so that the initial movement and the resulting flow out of the chamber 11 are limited. If, however, the excessive pressure persists, the fluid in the space 34 has enough time to flow via the throttle point 35 into the uncovered space 33 and the low pressure chamber 12, so that the spring 30 is also compressed and the flange 32 to is moved to the left. Due to the movement of both springs, the spring device has a smaller spring constant than each of the springs on its own, so that the valve member 23 is normally opened as far as necessary and sufficient fluid is released from the Karnmar 11 until the pressure in it on the for the The valve member's typical maximum pressure has fallen.

The preload ** and damping device thus enables a fast, but limited, undamped movement of the valve member and a hydraulically damped and precisely controlled opening longitudinal movement of the same; The attenuation by the Fluidraurn 34 and the arrangement of two springs enables reading of gro ~ Fjon Strömungüfiiengen from the Kinine.r Ii, without the valve operates instabi.1, pressure peaks occur with the valves in undamped otherwise typical night ilen _u the attenuation also results in a softer and quieter function of the valve, avoids bouncing of the valve and reduces vibrations, which improves the operation and service life of the pressure reducing valve.,

BATH ORIGINAL

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The rapid opening of the pressure reducing valve is particularly beneficial in the case of sudden, short pressure surges in the chamber 11. In such a case, the spring 29 is pressed slightly against the flange 32 and allows a limited flow out of the chamber 11, the valve member 23 quickly in the closed Position returns as soon as the pressure in the chamber has dropped to the maximum value again ο Such behavior is particularly advantageous compared to known constructions, in which pressure peaks cause undesirable operating behavior of the valve ο One would equip known pressure reducing valves with damping properties, as they are with the valve can be achieved according to the invention by the spring 30 in connection with the damping chamber 3U, the valve would respond much too slowly to pressure surges, so that excessively high pressure peaks would occur in the hydraulic system Address are h In contrast, relatively little damping and therefore work unstably. When normal pressure forces occur - in contrast to pressure surges - the valve would be opened too far and too much fluid would be drained from the pressure chamber so that the pressure in it drops too far swinging movement of the valve member caused the pressure reducing valve according to the invention combines a fast response to pressure shocks in the chamber 11 with a vibration-= 'and bounce-free operation ₀ the undamped spring member speaks at a fast pressure changes during the damped spring member additionally during longer press-in Activity occurs »

The pressure reducing valve according to the invention can be used instead of conventional pressure reducing valves, since the length of the springs 29 and 30 together is approximately equal to the length of a corresponding single spring. This is due to the arrangement of springs 29 and 30 _{0 one} behind the other. These springs can also be of different lengths, Z ₅ B ₀ a short spring 29 and a long one

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ίΟ57363

Include spring 30, depending on the desired properties of the pressure reducing valve.

In order to increase the effectiveness of the pressure reducing valve according to the invention show, they were compared with a conventional pressure reducing valve of identical construction, which a single spring ale The usual valve showed a good response behavior in the event of a shock load in the form of a very low pressure of IUlatü at an opening pressure of the Valve from 123 atm. Since this valve was undamped like all known fast-responding valves, it tended to vibrate, which resulted in excessive wear and tear and noise. This also resulted in a large range of pressure change of about 70 atmospheres in the high pressure chamber.,

In the valve according to the invention, the coil springs 29 and 30 were wound from a wire with a diameter of 2.6 mm. The spring 30 had a spring constant of 137 kg / cm and was 2 cm long, while the spring 29 had a spring rate of 192 kg / cn and was 1.6 cm long. Hole 18 had a clear width of 1.32 cm, while the edge of the flange 32 had a diameter of 1 * 30 approx, so that an annular gap as a throttle opening 35 of 0.1 mm wide stayed. This valve was set to an opening pressure of 123 atm set in the chamber 11 at a counter pitch of 11 atmospheres in the low-pressure chamber 12, by means of a suitable needle valve. The pressure in the chamber 11 became jerky with a Elevation speed increased from 7000 atmospheres per lake. After the uff · » nen of the valve due to the shock load occurred in the chamber 11 only a pressure change of 17 atm at a peak pressure of in the atü, which is an improvement in the response behavior against * over a normal valve corresponds to twice as much. Through the additionally achieved better stability, which occurs through the reduced pressure changes, also became a bouncing of the valve element "vibrations of the same and an over /" ratA.ig "

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Noise development avoided «The pressure reducing valve according to the invention has an improved response despite reduced tendency to bounce and vibrations.

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Claims (1)

Claims Pressure reducing valve with a valve housing having an inlet and an outlet, which has a valve seat on the inlet side, against which an axially movable valve member is prestressed by means of a spring device, the valve member in the raised position producing a flow connection between the inlet and the outlet, characterized in that that the spring device comprises an undamped spring member and a damped spring member, whereby = with the arrangement is made so that when a certain pressure is exceeded, the undamped spring member is mainly actuated first vii.rd, 2. Pressure reducing valve according to claim 1, characterized in that g e k e η η - 2. α i η et _# atüi u ^ s spring links screw muck springs (/.'9,3O) are provided. "S c, Crackfflij: darveä: til according to claim 2, characterized in that the coil springs (29 * 30) are unexposed in a zy ~ ii ^ drisoben hollow space (33,3 ^) and through a partition C31 _s 32) are separated from each other, and that the partition wall forms a Uronsalscelle (33) between the Fluidrc'Iumen (33,34) of the springs aufvi ^ huicndtsn cavity. kTiiiiHttr>'üitix according to claim α, thereby geke η η ζ e ι, ch Γι e «; , oass the partition as standing radially outward ·; > Flan ach eir.es into the interior of the spring (29) r ίΤ θ η dt: η, lapfiiiis i'dl) civis formed. nti. l according to claim 4, characterized in that g e k e η η I c h η e t, ciafe the cones C 31 > on that of the outlet side 1 0 9 8 2 / * / η 3 6 of the movable valve member (23) adjacent end is conical. 6. Pressure reducing valve according to claim i to 5, characterized in »that the undamped spring member (23) is arranged adjacent to the movable valve member (23) 7 ο pressure reducing valve according to claim 3 to 6 »characterized by g e that the throttle point through an annulus is formed between the outer edge of the flange (32) and the inner wall of the cavity (33,3H) * 8, pressure reducing valve according to claims 1 to 7, characterized in that the spring device is arranged one behind the other Includes spring members. 9. Pressure reducing valve according to claim i to 8, characterized in that the spring members are accommodated in the cylindrical cavity (33,34) of a valve housing (15), which is open on one side, that a valve seat part (16) in the open end of the valve housing ( 15 is inserted) snugly in that the movable valve member is inserted into the valve seat member (16) (23) and nit its one _r conical end (27) is biased against a valve seat (22) located on the inlet side (11) of the pressure reducing valve that the movable valve member (23) rests at its other end on the undamped spring member (29), and that the valve housing (15) has transverse bores (20) in the area of the discharge chamber (12). 10 ο Pressure reducing valve according to claim 9, characterized in that the movable valve member (23) has recesses (25) on the side facing the spring member _e 109824/1136 L e r p a g e